Rotary steam boiler

ABSTRACT

A rotary steam boiler comprises a rotatable member mounted in a housing including heating means. The rotatable member comprises a shaft with a plurality of axially extending ducts arranged about the shaft and a plurality of pipes each having opposite ends connected to one of said ducts and having a spiral configuration, the pipes extending radially about the shaft. Inlet and outlet heads are positioned at opposite ends of the ducts, respectively, and are arranged to communicate with the ducts during rotation of the shaft whereby steam may be continuously directed through the ducts and pipes to heat the steam as the shaft rotates. A preheater and a superheater increase the efficiency of the rotary steam boiler. The rotary steam boiler may be adapted for use with nuclear power stations.

BACKGROUND OF THE DISCLOSURE

This invention relates to a rotary steam boiler, which is an improvementwith respect to the boiler disclosed in U.S. Pat. No. 4,165,615 issuedAug. 28, 1979 to Paune Morcov. The patent describes and claims apparatusfor increasing the pressure and temperature of exhaust steam from theturbine in power stations.

The conventional condenser is eliminated because it requires a lot ofwater (60-100 times as much as steam). This first apparatus comprises atleast one pair of contrarotating drums each containing spirally coiledpipe and located within a casing so that successive sections of eachdrum pass in sequence through one heated zone (2 quadrants) a neutralzone and a cooled zone. As a rezult of the temperature rise in the hotsector and an exchange of steam between the two drums, the pressureincreases until it reaches its required value. This is the only methodto increase the pressure of a gas in a "isochore" way, with the usualtemperatures (700°-800° C.) that can be endured by the boiler material.

In the above mentioned patent the drum is provided with holes throughwhich the steam passes from one section to another. Packings pressedhydraulically on the outer surface of the drum shaft are situated in theinterior of the drums. Consequently they are not easily accessible. Inthe present application a single drum is provided in which lengths ofspiral piping form a plurality of individual sections which are spacedaround a central rotatable hollow shaft which is provided with ductsinterconnecting the sections, and which has a receiver-head at one endand an outlet head at the other end. The new construction is more solid,simple and consequently more reliable. The third sector disclosed in theabove-mentioned patent has been eliminated. It has been replaced by alow-pressure chamber which functions as an air-preheater and raises thethermic efficiency.

SUMMARY OF THE INVENTION

The pressure regenerator of the new construction comprises only onedrum, containing conduit means arranged in a radial-spirals (sections)through which the exhaust fluid flows in succession from thereceiver-head to the outlet-head.

The drum is located in a cylindrical housing which is divided into twoparts: warm and neutral. During rotation of the drum, the exhaust steamis heated (190° to 500° C.) in the warm zone and consequently thepressure increases from 11 atm to 100 atm at the discharge point, after180° rotation. Here a predetermined quantity of steam is delivered asfresh steam back to the turbine. In the second zone the "rest-pressure"will be successively delivered to the sections in the first zone,excepting the last 45° where the sections are connecting with alow-pressure chamber. The apparatus can be heated by a combustion sourcewithin the housing, or by an external source.

In a power station with nuclear energy, this apparatus can be utilizedas a heat exchanger and where it is substituted for the condenser.

BRIEF DESCRIPTION OF THE DRAWINGS

The new construction of the pressure regenerator will now be describedin detail with reference to the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view of the apparatus according tothe invention.

FIG. 2 is a transverse sectional view of the apparatus of FIG. 1.

FIG. 3 is a vertical sectional view of the outlet-head.

FIG. 4 is a vertical sectional view of the receiver-head.

FIG. 5 is a transverse sectional view of the apparatus for use in anuclear power station.

FIG. 6 is a longitudinal sectional view of the apparatus of FIG. 5.

FIG. 7 shows diagrammatically the thermodynamic specifications of thesteam in the example set forth in the specification.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1 and 2, the pressure regenerator comprises a centralaxle 1, which consist of 12 profiled pipes 6, which are welded together.At the one end it is provided with a coupler 8, which is connected withthe gear 7, whereas the other end is equipped with an outlet-head 4. Thereceiver-head 3, is connected with the exhaust steam line as shown inFIG. 4.

The drum-axle is mounted on two bearings 2, and the sections 5 arearranged radially. They consist of coiled pipes, the ends of which arewelded with a profiled pipe of the axle 1. The drum revolves in a closedspace 15, which is equipped with a burning unit 9, with a superheater10, and an exhaust gas line 18. The air passes through a low-pressurechamber 14, then through the air-superheater 10. From here it flowsthrough the pipe line 19 and sector II to the burner 9.

As illustrated in FIGS. 1 and 2, the first sector (180°) is providedwith 6 sections. The first section has been charged with exhaust steamfrom the receiver-head, while the sixth section has been discharged bythe outlet-head. The next four sections receive steam from the sectionsin sector II (i.e. 7,8,9,10).

The last two sections of sector II are connected with the low-pressurechamber 14, i.e. section 11 and 12.

In the low-pressure chambre the steam is cooled until it reaches itsminimum pressure. Then it passes on-together with the exhaust steam fromthe turbine-in the section 1. And now while the drum is turning, thesections pass through sector I.

The temperature rises, new steam is let in and consequently the pressureincreases until it reaches its normal value.

As can be seen in FIGS. 3 and 4 the packings between the differentsections are secured by plates 11, which are pressed hydraulically uponthe axle. The hydraulic pressure comes from an oil-pump 12, which issituated in the gear box together with a cooler 13. In this way theproblem of greasing the rubbing surface is eliminated.

In nuclear power stations, this apparatus can be utilized asheat-exchanger, as illustrated in FIG. 5, where one half of the drum isimmersed in a bath of liquid metal 18, which serves as a conductor ofheat. This can be, for example, mercury or another soft metal alloy(lead or tin, etc.) which melts at a temperature of less than 200° C.The housing 16 is provided with pipes 17 which are passed through thebath of liquid metal and are connected to the primary circuit of thereactor. The reactor heat is taken in by the sections of the pressureregenerator and the deeper the drum is immersed in the bath, the largerbecomes sector I (hot). The space over the bath is sector II (neutral).

EXAMPLE

On example of the invention is based on the following presuppositions:

The thermodynamic specifications of a pressure regenerator with a powerof 50,000 kw. we find in Table 1. Two apparatus supply one 100,000 kwturbine. On the right part are the pressure variations, which take placein the sections.

fresh steam with p=100 atm, t=500° C. spec.vol.=0.033 mc/kg steamquantity m=180 kg/sec

exhaust steam with p=11 atm, t=190° C. spec.vol.=0.185 mc/kg

According to the Mollier diagram, the temperature drop is=575Kjrespective 137.5 kcal/kg.

The power: L_(kgm) =180×137.5×427×0.97=10,250,000 kgm orL=10,250,000/75=136,000 H.P.=100,000 kW.

We have chosen two apparatus with a performance of 90 kg/secrespectively 325 t/h with 12 sections (cells) and 60 revolutions perminute, i.e. 6 cells in sector I (hot) (see FIG. 2) and 6 cells insector II, four of which are connected with sector I and another twowith the low-pressure chamber.

When choosing the volume of the section it must be taken into accountthat 90: 12=7.5 kgs of fresh steam shall be delivered at the dischargepoint.

According to FIG. 7 at this moment the cell is charged with 50.68 kgs ofsteam (117 atm, 502° C.). After 7.5 kgs of steam have been discharged43.18 kgs of steam will still remain in the cell. Taking into accountthe specific volume of this steam (v=0.03 mc/kg the volume of the cellmust be:

    V=0.03×50.68=1.50 m.sup.3

The state equation of steam is: PV=GRT i.e.

P=117×1033=12,086,000 kg/m²

V=cell volume=1,50 m³

G=steam weight=51 kgs

R=steam constant=47

T=absolute temperature=502+273=775° K.

countertest:

PV=12,086,000×1.50=1,850,000=GRT=51×47×775

For the coiled pipes we have chosen a pipe of 76.1×4 mm with a crosssection of F=35.3 cm².

The length of the coiled pipe is:

    L=1.50/0.00353=535 m

The outer surface is: F_(a) =0.24×435=105 m².

That means that we are dealing with a double spiral, each spiral with 5windings of the total dimension 3.5×1.5 m. Consequently our drum has adiameter of about 3 m (FIG. 2). The heat quantity which is required percell (section)-see FIG. 7-is calculated as follows: ##EQU1##

The other heat quantity for 42.0 kgs of steam which fluctuates betweenthe sections 7 and 10 in sector II and the sections 2 and 5 in sector I,is only of importance for the heat loss which is caused by conductionand radiation concerning the burning unit (see heat balance). Theaccording calories for steam and air-heating are required to heat thecoiled pipes in sector I that have precedingly been cooled in sector IIby about 5° C.

Heat transmission:

The 1197 Kcal/section are received by the steam and have to pass thewall of the pipe (by means of conduction, convection and radiation):##EQU2##

The cooling:

The low-pressure chamber has been calculated in the same way as a heatexchanger (steam-air) since it functions as air-preheater. Thetemperature drop is: ##EQU3##

As demonstrated in FIG. 1 (pos14) the air is preheated at first in thelow-pressure chamber, afterwards in the smoke gas air-preheater, andfinally in sector II.

The heat balance/sec.: ##EQU4##

It must be observed that the degree of efficiency (for boiler andcondenser) amounts to a maximum of 40-42%. With conventional plantsnowadays used, generally it is 32-34% with power stations that areexclusively provided for the production of electricity.

I claim:
 1. A rotary steam boiler comprising:(a) a housing defining achamber and including heating means to heat a first sector of saidchamber, the remaining sector of said chamber being cooler; (b) anassembly mounted for rotation about an axis in said chamber, saidassembly comprising a plurality of elongated, open-ended ducts arrangedin an annular configuration about said axis and extending substantiallyparallel to said axis and a plurality of heat exchange means arrangedradially about said annular arrangement of ducts, each of said heatexchange means being connected to one of said ducts to permit steam tocirculate between each of said ducts and the associated heat exchangemeans; and (c) an annular receiver head and an annular outlet head insealing engagement with opposite ends of said plurality of ducts,respectively, said receiver and outlet heads being arranged tocommunicate with said plurality of ducts during rotation of saidassembly; (d) said heating means comprising a burner and conduit meansfor feeding fuel and air to said burner, a preheater, a superheater,said conduit means for said air being arranged to pass through saidpreheater, and further conduit means passing through said superheater,said receiver head being arranged to direct steam into said assembly andsaid preheater such that said air supply to said burner is preheated bysaid steam during passage through said preheater; (e) whereby steam maybe directed through said receiver head, said ducts, said plurality ofheat exchange means and said outlet head and may be heated in said heatexchange means during passage of said heat exchange means through saidheated first sector of said chamber.
 2. A rotary steam boiler accordingto claim 1 wherein said heated first sector of said chambersimultaneously accommodates a plurality of said heat exchange means. 3.A rotary steam boiler according to claim 1 wherein said annular receiverhead includes conduit means for transmitting steam from successive ductswhile located at at least one predetermined fixed position to successiveother ducts while located at at least one other predetermined fixedposition during rotation of said assembly, whereby partially heatedsteam from selected heat exchange means may be recycled to otherselected heat exchange means for further heating in said heated firstsector during rotation of said assembly.
 4. A rotary steam boileraccording to claim 1 wherein each of said heat exchange means comprisesa pipe formed in a spiral configuration with the opposite ends thereofconnected to one of said ducts.